CARACTERIZAÇÃO MOLECULAR E AVALIAÇÃO DO POTENCIAL DE PRODUÇÃO DE TRICOTECENOS PELAS ESPÉCIES Fusarium meridionale, F. austroamericanum e F. graminearum

Abstract

Wheat fusarium head blight (FHB) is a devastating disease in wheat fields in Brazil and around the world. Researchers have sought to learn about the etiological agents of this disease to propose improvements in the management and development of cultivars with a better response to the attack of the potogen. The main fungi that cause FHB belong to the Fusarium graminearum species complex (FGSC). These fungi produce mycotoxins that can make the use of wheat grains unviable to the industry. The State of Paraná is the largest wheat producer in Brazil and the genetic characterization and the potential for mycotoxins production of FGSC members occurring in the state is an important advance for the development of wheat production in the state. In this sense, the goals of this study were: 1. genotyping by PCR (polymerase chain reaction) 56 isolates of FGSC from wheat fields of PR; 2. quantify and evaluate the production potential of mycotoxins deoxynivalenol and its acetylated derivatives 3-ADON, 15-ADON and nivalenol, by FGSC isolates, grown in wheat plants and in rice medium; 3. evaluate the inhibition potential of mycelial growth among isolates with 3-ADON and 15-ADON genotypes in relation to the growth of isolates with NIV genotype; 4. evaluate the existence in the state of Paraná of genotypes capable of simultaneously producing significant and similar amounts of mycotoxins NIV and 3-ADON or NIV and 15-ADON. 5.Evaluate the genetic diversity and genetic structure of populations of the species F. graminearum (Fgra), F. meridionale (Fmer) and F. austroamericanum (Faus), sampled in wheat fields of the state of Paraná. The results of the genotyping of the Tri3 and Tri12 genes showed efficient and confirmed the presence of FGSC isolates with NIV, 3-ADON and 15- ADON genotypes in the state of PR. The evaluation of mycotoxin production potential by ultra-performance liquid chromatography–tandem mass spectrometry showed that the species Fmer, Faus and Fgra were efficient in the production of one or more toxins. Fmer was efficient in producing only NIV. Faus showed high variability in the production of 3-ADON and DON and low and homogeneous production of 15-ADON and NIV. Fgra was effective in the production of 3-ADON in wheat plants and in the production of 15-ADON and DON in rice medium and in wheat plant. The rice medium influences the amount of mycotoxins produced by Fmer and Fgra. The isolates of the species Fgra and Faus did not inhibit the growth of Fmer isolates. No hybrid genotypes, capable of simultaneously producing significant amounts of mycotoxins NIV and 3-ADON or NIV and 15-ADON or NIV and DON, were observed. The evaluation of populations of the species Fgra, Fmer and Faus using inter-simple sequence repeat (ISSR) markers identified high diversity and genetic structure in populations. Fgra showed the high genetic diversity among the studied species. The overall analysis of the data obtained in this study shows the diversity of mycotoxins produced by members of the FGSC from Paraná, with NIV and DON being of greater relevance for monitoring wheat grains harvested in the state to guarantee human and animal food security. Also, the high diversity and genetic structure can guarantee high resilience of these species, making it difficult to obtain wheat cultivars with good FHB resistance, and also making chemical control less effective.